Seborrheic keratosis

The term is a misnomer because Seborrheic keratoses result from a proliferation of keratinocytes and are not related to sebaceous glands. Therefore, these keratoses should not be termed seborrheic.


Seborrheic keratoses are the most common benign tumor encountered in older individuals, present in 80-100 percent of people over age 50. The exact etiology is unknown, but cumulative exposure to sunlight is likely involved. Clinically, they are brown verrucous plaques with a stuck-on appearance. Although they can be found anywhere on the body excluding the palms, soles, and mucosal membranes, they are most often located on the trunk, dorsal hands, and face. Therefore, they are not limited to a seborrheic distribution.